Abstract
Abstract
Cerebrovascular endothelial function can be assessed by measuring the shear‐mediated dilation or cerebrovascular reactivity (CVR) of the internal carotid artery (ICA) in response to transient hypercapnia (30 s). ICA CVR is blunted with aging; however, it is not known whether age‐related reductions in ICA CVR are influenced by antioxidant‐responsive mechanisms. The purpose of this study was to determine whether infusion of the antioxidant, ascorbic acid (AA) restores ICA CVR in middle‐aged and older (MA/O) adults. We also examined the effect of AA on middle cerebral artery (MCA) CVR to sustained (3‐min) hypercapnia. We hypothesized that MA/O adults would exhibit lower cerebrovascular function compared to young (Y) adults, and that infusion of AA would improve cerebrovascular function in MA/O adults, whereas infusion of saline (SAL) would not. The primary analytic sample included nine Y adults (25 ± 2 years) and nineteen (65 ± 6 years) MA/O adults, with analyzable data varying by outcome. ICA CVR was measured using high‐resolution duplex ultrasound, and MCA CVR was measured using transcranial Doppler ultrasound. AA infusion improved ICA CVR and MCA CVR in MA/O adults but had no effect in Y adults. These findings suggest that age‐related impairments in cerebrovascular function may be partly attributable to mechanisms responsive to acute, supraphysiological AA administration.